In a typical radio communications network, wireless terminals, also known as mobile stations and/or user equipments (UEs), communicate via a Radio Access Network (RAN) to one or more core networks. The RAN covers a geographical area which is divided into cell areas, with each cell area being served by a base station, e.g., a radio base station (RBS), which in some networks may also be called, for example, a “NodeB” or “eNodeB”. A cell is a geographical area where radio coverage is provided by the radio base station at a base station site or an antenna site in case the antenna and the radio base station are not collocated. Each cell is identified by an identity within the local radio area, which is broadcast in the cell. Another identity identifying the cell uniquely in the whole mobile network is also broadcasted in the cell. The base stations communicate over the air interface operating on radio frequencies with the user equipments within range of the base stations.
In some versions of the RAN, several base stations are typically connected, e.g., by landlines or microwave, to a controller node, such as a radio network controller (RNC) or a base station controller (BSC), which supervises and coordinates various activities of the plural base stations connected thereto. The RNCs are typically connected to one or more core networks.
A Universal Mobile Telecommunications System (UMTS) is a third generation mobile communication system, which evolved from the second generation (2G) Global System for Mobile Communications (GSM). The UMTS Terrestrial Radio Access Network (UTRAN) is essentially a RAN using Wideband Code Division Multiple Access (WCDMA) and/or High Speed Packet Access (HSPA) for user equipments. In a forum known as the Third Generation Partnership Project (3GPP), telecommunications suppliers propose and agree upon standards for e.g. third generation networks and further generations, and investigate enhanced data rate and radio capacity.
Specifications for the Evolved Packet System (EPS) have been completed within the 3GPP and this work continues in the coming 3GPP releases. The EPS comprises the Evolved Universal Terrestrial Radio Access Network (E-UTRAN), also known as the Long Term Evolution (LTE) radio access, and the Evolved Packet Core (EPC), also known as System Architecture Evolution (SAE) core network. E-UTRAN/LTE is a variant of a 3GPP radio access technology wherein the radio base stations are directly connected to the EPC core network rather than to RNCs. In general, in E-UTRAN/LTE the functions of a RNC are distributed between the radio base stations, e.g., eNodeBs in LTE, and the core network. As such, the RAN of an EPS has an essentially “flat” architecture comprising radio base stations without reporting to RNCs.
There are two common ways of defining and signaling desired resource demands to a bottleneck in the radio communications network. A bottleneck being a location in the radio communications network where a single or limited number of components or resources affects capacity or performance of the radio communications network.
The first common way is to pre-signal/pre-configure the desired resource sharing rules for a given traffic aggregate, such as a flow or a bearer, to the bottleneck node prior the arrival of the actual traffic. The bottleneck node then implements the handling of the traffic aggregates based on these sharing rules, e.g. uses scheduling to realize the desired resource sharing. Examples for this pre-signaling/pre-configuration method are e.g. the bearer concept of 3GPP [3GPP TS 23.401], SIRIG [3GPP TS 23.060 section 5.3.5.3], or Resource Reservation Protocol (RSVP) [RFC2205]. An example scheduling algorithm for this method, implementing the 3GPP bearer concept at an LTE eNB, can be found in Wang Min, Jonas Pettersson, Ylva Timner, Stefan Wänstedt and Magnus Hurd, Efficient QoS over LTE—a Scheduler Centric Approach. Personal Indoor and Mobile Radio Communications (PIMRC), 2012 IEEE 23rd International Symposium. Another example for this is to base the resource sharing on Service Value as described in Service Value Oriented Radio Resource Allocation, Invention disclosure, PCT/SE2011/051475.
The second common way is to mark packets with drop precedence, which marks the relative importance of the packets compared to each other. Packets of higher drop precedence are to be dropped before packets of lower drop precedence. An example for such method is DiffServ Assured Forwarding (AF) within a given class [RFC2597]. Also such a method with several drop precedence levels are defined in a Per-Bearer Multi Level Profiling, European Patent Application No. 12167141.6.
It is an open issue how to signal service policies to different resource bottlenecks, including both transport bottlenecks and radio links. The term service policy in this document denotes instructions on how the available resources at a packet scheduler shall distribute the available, primarily transmission, resources among the packets of various packet flows arriving to the scheduler. The term ‘resource sharing rules’ is used in the same meaning. In the case of radio links, the service policy also needs to define how a terminal dependent radio channel overhead should affect the resource sharing. Such a scheme for signaling is preferably simple, versatile and fast adapts to the actual congestion situation.
Pre-signaling/pre-configuration solutions can describe rich set of different resource sharing policies. However these policies
a) have to be configured in advance of actual traffic at all bottlenecks, or
b) have to be signaled before the first packet of the flow arrives.
Option a) limits the flexibility of policies, and the pre-configuration of a large number of resource sharing policies takes node resources to maintain which can make it costly. Option b) adds a setup delay and overhead before the first packet can be delivered. In addition, these solutions usually require traffic handling on a per aggregate/flow basis, e.g., to have separate queues per traffic aggregate/flow and implement a per traffic aggregate/flow resource sharing mechanism. While in some cases it is possible to have this, e.g. per bearer handling over air interface, in other cases this puts additional complexity on the system, e.g. over RAN Transport Network (TN) bottlenecks or within bearer differentiation.
Drop precedence marking solutions, as mentioned above, are limited by the interpretation of drop precedence, leading to a limited non-flexible handling of the packets in the radio communications network.